Incandescent lamp



A. R. DENNINGTON.

INCANDESCENT LAMP.

APPLICATION FILED MAR-16.1915.

1,313,857. Patented Aug. 19,1919.

WITNESSES: INVENTOR 2 6 40. M fllfiar flew/70777? UNITED STATES PATENT OFFICE.

ARTHUR R. DENNINGTON, OF EAST ORANGE, NEW JERSEY, ASSIGNOR TO WESTING- HOUSE LAMP COMPANY, A CORPORATION OF PENNSYLVANIA.

Application filed March 16. 1915.

To all whom it may concern:

Be it known that I, Airmen R. DENNING- 'rox, a citizen of the United States, and a resident of East Orange, in the county of Essex and State of New Jersey, have inventeda new and useful Improvement in Incandescent Lamps, of which the followin" is a specification.

y invention relates to incandescent elec tric lam s particularly adapted for projection wol li, and it has for an object to provide a lamp of the character specified that will generate the requisite amount of light in such manner as to insure its uniform distribution over the entire field of illumination.

Another object of in invention is to provide a filament mounting that will be simple and rugged in construction and so arranged that a maximum amount of filament may be disposed in operative relation to the lens system of the projecting device.

In the accompanying drawings, Figure 1 is a side view, in elevation, of an incandescent lamp embodying my invention; Fig. 2 is a diagrammatic view of my lamp together with a coacting reflector and lens to illustrate the particular utility of the lamp in connection with projecting sys tems; and Figs. 3 and 4 are enlarged views, in plan and elevation, respectively, of the filament of my improved lamp, showing the specific arrangement of the component parts thereof.

The ideal source of illumination for projection work is a point because of the fact that all lens systems have a definite focal point and it is essential for clear images that the light proceed as nearly as possible from the focal point. Though the ideal condition is impossible of attainment. such condition is approximated as nearly as possible in the design of projecting lamps. By my invention, I form the filament of a projection lamp into a plurality of closelywound coils and mount these coils in such manner, adjacent to the focal point, that each is enabled to project a maxlmum portion of its illumination in the desired direction. By the use of my invention, especially when employing filaments of drawn tungsten wire mounted in an inert atmosphere, such, for example, as nitrogen or argon, I am enabled to produce illuminating effects of such intensity and clearness Specification of Letters Patent.

Patented Aug. 19, 1919.

Serial No. 14,859.

as to displace the ordinary are lamp for projecting purposes in a majority of cases. The advantages of an incandescent lamp over an arc lamp for this work are marked, since the incandescent lamp is perfectly uniform in light intensity and, furthermore, needs but little care on the part of the operator.

Referring to the accompanying drawing for a more detailed description of one embodiment of my invention. I have shown the container of an ineamleseent lamp at 5 in Fig. 1. The container is provided with a base (3 of the usual type having an inwardly projecting stem 7 through which extend the current-can'ying leads 8-8. A filament 9 is mounted it )on the leads 8 and comprises a plurality of closely wound helical coils 1()l(). .-\s more clearly shown in Figs. 3 and -l, some of the coils 10 are mounted in a row with spaces intervening therehetween, and the remaining coils are mounted in an adjacent row in staggered relation to the first mentioned coils so that the light emitted therefrom is able to shine through said intervening spaces. The intervening spaces in the firstrow of coils are substantially equal in width to the diameter of the latter coils so that the projections of all the coils upon a plane normal to the projecting axis of the lamp are contiguous. The illumination of a screen or other object deriving light from said filament will therefore be substantially uniform throughout and free from objectionable dark spots or zones. I have illustrated in Fig. 4 the manner in which the different coils of the filament entirely cover a certain well defined zone of illumination when viewed along the projecting axis of the lamp.

In Fig. 2 is shown a lamp 11 constructed in accordance with my invention and mounted adjacent to a reflector 12, which may be of the parabolic type so that the focal point 13 of said reflector lies at approximately the center of the mass of coils 10, or a reflector of different form may be employed provided the center of the mass of coils is properly located with reference thereto. Light emitted from the lamp 11 is transmitted, either directly or after reflection from the reflector 12. through a projecting system usually consisting of a condenser system and projecting lens, as illustrated, for example, by a double convex lens 14. I find that, b the use of high-cflicicncy lamps of the c aracter described, I am able to generate a suficlent amount of light in such proximity to the focal point of the reflector 12 as to constitute a point source for all practical purposes, it being found that the images projected upon a screen are remarkably clear and distinct.

\Vhilc I have illustrated my invention in but one specific embodiment thereof, it is obvious to those skilled in the art that it is susceptible of various minor changes and modifications without departing from the spirit thereof, and I desire, therefore, that only such restrictions shall be placed thereupon as are imposed by the prior art or are specifically set forth in the appended claims.

I claim as my invention:

1. In an electric incandescent projection,

lamp, a 'filament comprising a plurality of straight coils of substantially equal size, approximately one-half of said coils being disposed in parallel relation to each other in a plane substantially normal to the projecting axis of the lamp and having spaces intervening thercbetween substantially equal in width to the diameter of said coils, and the remaining coils being disposed behind said first named coils and in line with said intervening spaces, whereby a substantially uniform illuminating zone comprising all of said filaments is presented in the direction of the projecting axis.

2. In an electric incandescent projection lamp, a filament comprising a plurality of substantially straight closely wound coils that are staggered with respect to, and spaced apart from, one another in the direction of the projecting axis of the lamp, the intermediate space between the coils of one row being completely bridged 'by a coil of another row in order that the several projections of the coils upon a plane normal to the projecting axis of the lamp may be contiguous, and means for supplying current to said filament.

In an electric incandescent projection lam a filament comprising a plurality of spaced and closely wound coils each capable of formin a band of light, said coils being so disposed in parallel relation to each other that their projection upon a plane normal to the projecting axis of the lamp are substantially contiguous.

4. In a light projecting device, a plurality of spaced and substantially parallel helical coils of incandescent material forming a plurality of bands of light, said coils being spaced from one another a distance not substantially greater than their diameter, and staggered with respect to one another so that in the aggregate they may produce the effect of a continuous source of light.

In testimony whereof, I have hereunto subscribed my namethis twenty-fifth day of February 1915.

ARTHUR R. DENNINGTON.

Witnesses:

E. G. Wnsron, G. A. WHITTEMORE. 

